Method and apparatus for stablizing the sub-grade of a railroad ballast bed

ABSTRACT

The sub-grade of a railroad ballast bed is stablized by depositing sand on the bed, removing the sand and ballast in admixture with an excavating bucket conveyor until the sub-grade has been exposed, the sand and ballast are separated from each other on a screen which receives the admixture, and two endless conveyors mounted below the screen convey the separated sand and ballast to the exposed sub-grade to deposit the separated sand thereat at a point ahead of a succeeding point where the separated ballast is deposited, thus depositing the ballast on a layer of sand interposed between the sub-grade and the ballast.

ilnite St i atent 1191 Teurer et al.

METHOD AND APPARATUS FOR STABLIZING THE SUB-GRADE OF A RAILROAD BALLAST BED Inventors: Josef Teurer, Vienna; Karl Fiilser,

Linz-Urfahr, both of Austria Franz Plasser Bahnbaumaschinen-lndustrie- Gesellschaft m.b.lH., Vienna, Austria Filed: Mar. 18, 1974 Appl. No.2 452,203

Assignee:

Foreign Application Priority Data Apr. 16, 1973 Austria 3338/73 U.S. Cl. 171/16, 104/2 lint. Cl. EOlb 27/04 Field of Search 104/2, 3; l7l/l, l6, 17

[ Mar. 25, 1975 3,624,936 12/1971 Yard 104/279 FOREIGN PATENTS OR APPLICATIONS 677,923 8/1952 United Kingdom 171/16 Primary Examiner-M. Henson Wood, Jr. Assistant Examiner-Richard A. lBertsch Attorney, Agent, or Firm-Kurt Kelman [57] ABSTRACT The sub-grade of a railroad ballast bed is stablized by depositing sand on the bed, removing the sand and ballast in admixture with an excavating bucket conveyor until the sub-grade has been exposed, the sand and ballast are separated from each other on a screen which receives the admixture, and two endless conveyors mounted below the screen convay the separated sand and ballast to the exposed sub-grade to deposit the separated sand thereat at a point ahead of a succeeding point where the separated ballast is deposited, thus depositing the ballast on a layer of sand in terposed between the sub-grade and the ballast.

8 Claims, 4 Drawing Figures A N 3 m mvQ Q N PATENTEUHARZSIBYS SHEETlBfZ METHOD AND APPARATUS FOR STABLIZING THE SUB-GRADE OF A RAILROAD BALLAST BED The present invention relates to improvements for stabilizing the sub-grade of a railroad ballast bed by means of a sand layer interposed between the sub grade and the ballast.

A substantial factor in the quality and durability of a railroad ballast bed is the nature of the sub-grade. Subgrade soil which is water-impermeable causes water stagnation after precipitation and subsequent softening of the soil. The lowest pieces of ballast accordingly penetrate into the softened sub-grade soil, thus slowly lowering the level of the bed and causing misalignments in the track grade.

To overcome this disadvantage, it has been proposed to place a layer of sand between the sub-grade and the ballast in a thickness of about 4 to 8 inches. Such a sand layer is water permeable and thus prevents softening of the sub-grade soil since the accumulating water is stored in the sand layer. Thus, no ballast will be displaced into the sub-grade soil.

The layer of sand was deposited on the exposed subgrade after a section of ballast had been removed therefrom, the deposited sand was planed down, and the ballast was then deposited upon the layer of sand. While this procedure seems logical and simple, it has some sufficiently serious disadvantages to prevent the use of this method in commercial track surfacing operations.-

The amounts of sand needed for laying down the required intermediate layer are considerable and must be brought to the working site by freight cars. This makes it impossible to preceed continuously and in sequence with the three steps: removing ballast, laying down sand, depositing ballast. Rather, the work must proceed section by section, which puts the track out of traffic for too long a period.

In an effort to overcome this disadvantage, British Pat. No. 1,174,930, published Dec. 17, 1969, proposes to remove a part of the sub-grade soil during a ballast cleaning operation, in which the ballast is excavated forcleaning, to mix the soil with suitable additives and binders, and then to deposit the reinforced soil again before the cleaned ballast is laid down. This avoids the need for large amounts of sand and makes the transport problem easier to solve so as to make continuous operations possible. However, the method is not economical because of the high price of the required additives to strengthen and consolidate the soil. Furthermore, the chemical and mechanical strength of the treated sub-grade soil is not assured for a long period of time.

It is the primary object of this invention to stabilize the sub-grade of a railroad ballast bed effectively in a continuous operation which interrupts regular train traffic as little as possible.

The above and other objects are accomplished in accordance with the invention by depositing sand on the ballast bed, removing the sand and ballast in admixture until the sub-grade has been exposed, separating the sand the ballast from each other, depositing the separated sand in a layer on the exposed sub-grade, and depositing the separated ballast on the layer of sand.

The present invention also provides an apparatus for stabilizing the sub-grade of a railroad ballast bed supporting ties fastened to track rails. The apparatus comprises means for removing a mixture of sand and ballast from the bed to leave an exposed section of the subgrade, and screening means associated with the removing means. The screening means receives the removed mixture and separates the sand from the ballast, and at least two endless conveyors are mounted below the screening means to receive the separated sand and ballast, to convey the separated sand and ballast to the exposed sub-grade section and to deposit the separated sand thereat at a point ahead of the succeeding point where the separated ballast is deposited. Means are also provided for sweeping sand off the ties and for planing the sand on the exposed sub-grade, which means are arranged between these points.

The above and other objects, advantages and features of this invention will become more apparent from the following detailed description of a now preferred embodiment thereof, taken in conjunction with the accompanying drawing wherein FIG. 1 is a schematic side elevational view of a mobile apparatus according to the invention and FIGS. 2 to 4 are enlarged views of structural details of the apparatus at the points of sand and ballast deposit in side elevational, top and front views, respectively.

The illustrated apparatus comprises frame I mounted on undercarriages 2, 2 for mobility on rails 3 of the track which are fastened to ties 4 resting on ballast bed 5. The ballast is supported on sub-grade soil 6. As shown at the left side of FIG. 1, sand 7 is first deposited on the ballast bed 5, whereupon the sand and ballast are removed or excavated in admixture by a conventional excavating chain or bucket conveyor 8 until the sub-grade has been exposed. Such ballast removing or excavating means are well known in the art of cleaning ballast, as is screening means 10associated with the removing means. Screen 10- receives the mixture of sand and ballast, and separates the sand! from the ballast. As will be described hereinafter in detail and as shown at the right side of FIG. I, the separated sand is then deposited in a layer on the exposed sub-grade and the separated ballast is deposited on the layer of sand so that the layer of sand comes to be interposed between subgrade 6 and ballast 5.

The means for removing or excavating the mixture of ballast and sand from the bed beneath the track to leave an exposed section of the sub-grade is designated as 8 and, as is common in the ballast cleaning art, the illustrated excavating means is a conventional endless bucket conveyor supported on frame 1 by hydraulic jack 9 to enable the conveyor to be vertically adjusted. Again as conventional, screening apparatus 10 is associated with the removing means 8, being mounted under the upper end of the removing means and rearwardly thereof, in the working direction, to receive the mixture of sand and ballast from the screening apparatus and to separate the sand from the ballast.

A guide or baffle means 11 arranged at the rear end of the screening apparatus serves to direct the separated sand and ballast separately to the associated portion of endless conveyor means. The conveyor means comprises two endless conveyor bands each comprising a center dividing web 12a keeping the sand and the ballast separated during conveyance on adjacent portions of the conveyor bands. As shown in FIG. 4, one endless conveyor band 12 is associate with each track rail 3, the conveyor band portions facing the center of the track conveying sand 7 while the outwardly facing conveyor band portions convey ballast 5.

It may be useful to provide means for pivoting each endless conveyor band 12 in a substantially horizontal plane, as shown in broken lines in FIG. 3, so as to facilitate the even distribution of ballast and sand over the entire width of the bed.

Guiding device 13 is associated with the output end of each conveyor band 12 and is arranged to direct ballast vertically downwardly, the illustrated guiding device, as best shown in FIG. 3, consisting of a segmental hood hinged to the output end of the conveyor to force the ballast vertically downwardly in the direction of the downwardly pointing arrows. The sand, on the other hand, is thrown free off the output end of the conveyor in a parabolic path, as indicated by the paraboliform arrows in FIG. 2. In this manner, the separated sand is deposited on the exposed sub-grade section at a point ahead ofthe succeeding point where the separated ballast is deposited, thus causing a layer of sand to be formed on the sub-grade and the ballast to be laid on topof the layer of sand. The path of the ballast may be adjusted by suitably pivoting hood 13, for instance, and the parabolic path of the sand may be changed by changing the speed of the conveyor band, if desired, thus adjusting the paths of the sand and ballast, depending on the nature of these materials.

Planing means 14 is arranged between the points of deposit of the sand and the ballast so that the deposited sand may be suitably planed down and compacted into a substantially even layer. Yielding jack 15 adjustably mounts the planing means on bucket conveyor 8 so as to enable the position of the planing means to be adjusted in conformity to the surface configuration of the sub-grade. If desired, a vibratory motor may be associ ated with the planing means to assure increased compaction of the sand layer.

As shown in FIG. 4, the width of the planing means 14 exceeds the length of ties 4 so that the planing means extends beyond the tie ends and provides an even and smooth support for the entire width of the ballast bed. However, if desired, the planing means may be so shaped as to provide a different sand layer'profile, such as a layer which is thicker underneath the rails and thinner therebetween.

Sweeping means is also arranged between the points of deposit of the sand and the ballast to sweep sand off the ties, the illustrated sweeping means comprising a sweeping device 16 associated with each track rail. Each sweeping device comprises longitudinal carrier 18 extending along and above each rail 3 to cover the same and four successive plow-like wiping plates 17 mounted on the carrier and extending transversely thereof, each in the shape of an arrow head and extending in oblique planes. The lower edges of the wiping plates are closely adjacent the upper faces of ties 4 so that, as the apparatus moves forwardly, the plates will sweep off any sand deposited on the ties and throw it unto the bed. At the same time, the wiping plates serve to direct the sand in its parabolic path downwardly. The carrier 18 protects the rails from falling sand and ballast, and also protects the area of the ties where the railfasteners are from being covered by sand, this area not being reached by the wiping plates.

The above-described apparatus operates in the following manner:

A desired amount of sand is deposited on an existing ballast bed which, if desired, was previously cleaned. Normally, about 1 ton of sand per meter of track will suffice. This first step in the operation causes practically no interruption in train traffic since a number of sand-carrying trains may be used to lay down the sand as they move over the track, and trains may freely move over all track sections on which sand has been deposited (as shown at the left side of FIG. I).

The following steps correspond roughly to those in conventional ballast cleaning procedures, no intermittent transportation of sand or additives being required, Y

so that any train interruptions due to this work are the same as in ballast cleaning operations.

Thus, after a stretch of track bed has been covered with sand, the mobile apparatus of the present invention is moved into position so that the excavating means 8 may remove the sand 7 and ballast 5 in admixture until the sub-grade has been exposed. The removed sand and ballast are conveyed by bucket conveyor 8 to screening apparatus 10 where the sand and the ballast are separated from each other. The baffle device 11 guides the separated sand to the two inwardly facing portions of the two endless conveyor bands l2, 12 while guiding the separated ballast to the two outwardly facing conveyor band portions.

At the output ends of the conveyors, the sand is thrown off the conveyors in an initially substantially horizontal path which then becomes parabolic and intersects wiping plates 16, the latter forcing the sand vertically downwardly onto the exposed sub-grade. The profiling or planing means 14, moving at a constant, adjusted distance above the plane of the sub-grade, then distributes the deposited sand over the entire width of the bed and causes some compaction of the sand, this compaction being reinforced by vibratory motor 19 mounted on the planing means. Any sand remaining on ties 4 is swept off by wiping plates 17 and falls on the compacted layer of sand just before the ballast is deposited at a succeeding point determined by the adjustment of segmental hood 13. In this manner, a profiled intermediate layer of sand is produced between the sub-grade and the ballast, and no mixture takes place between the sand and the ballast.

In view of the different angles of the paths of the sand and the ballast, as they are thrown off the output ends of the conveyors, it is advantageous to deposit the sand between the rails while the ballast is deposited primarily in the region of the tie ends and then plowed inwardly between the rails.

The arrangement of the two adjacently running conveyor bands 12, 12 makes it possible to reduce the length of the track section remaining unsupported by ballast to a minimum, thus assuring a machine length between the two undercarriages which is not excessive. This is an important consideration in dimensioning the support structures of the apparatus. Furthermore, the apparatus frame may carry further ballast working tools, as may be desired in ballasting operations.

A particularly simple structure is obtained in the illustrated embodiment by arranging the conveying means as endless conveyor bands l2, 12 for pivoting in a horizontal plane, mounting a center dividing web on each conveyor band to keep the sand and ballast separated during conveyance, and to use a guiding device for the ballast at the output end of the conveyors. It would also be possible to provide a single endless conveyor provided with two dividing webs dividing the conveyor into a center portion and two side portions, the center portion conveying the separated sand and the two side portions conveying the separated ballast. Such a single conveyor would extend substantially over the entire width of the track bed and would be driven by a single power source. However, two separate conveyors, each associated with a respective rail, are lighter in weight than a single massive conveyor.

The thickness of the deposited sand layer may be kept as constant as possible by mounting the planing means 14 vertically adjustably. Thus, if the sub-grade surface is uneven, it will force the planing means up and down in conformity with the sub-grade surface configuration so that the thickness of the sand layer will remain unchanged.

Horizontal swinging of the conveyor bands 12 will cause the ballast to be deposited on the sand layer in a rather even layer, even without special smoothing operations, particularly since the wiping plates 17, which sweep sand and ballast off ties 4, also have the effect of smoothing the surface ofthe ballast layer. However, if desired, additional plow means may be mounted on the apparatus or follow the same to provide any desired ballast bed profile.

After the above-described operation has been completed, the bed provides a sufficiently firm track sup port to enable conventional mobile track correction apparatus to travel over the track for leveling and/or lining the same.

What we claim is:

l. A method of stabilizing the sub-grade ofa railroad ballast bed, comprising the sequential steps of l. depositing sand on the ballast bed,

2. removing the sand and ballast in admixture until the sub-grade has been exposed,

3. separating the sand and the ballast from each other,

4. depositing the separated sand in a layer on the exposed sub-grade, and

5. depositing the separated ballast on the layer of sand.

2. The method of claim 1, wherein ties fastened to track rails are supported on the ballast bed and some ofthe separated sand is deposited on the ties during deposition on the sub-grade, comprising the further steps of sweeping the sand off the ties and planing the sand down on the exposed sub-grade.

3. The method of claim 1, wherein ties fastened to two track rails are supported on the ballast bed and the separated sand is deposited between the rails while the separated ballast is deposited on the layer of sand by throwing at least a major portion of the separated ballast in the region of the ties ends and plowing it inwardly between the rails.

4. An apparatus for stabilizing the sub-grade of a railroad ballast bed supporting ties fastened to track rails, comprising 1. means for removing a mixture of sand and ballast from the bed to leave an exposed section of the sub-grade,

2. screening means associated with the removing means, the screening means receiving the mixture and separating the sand from the ballast,

3. at least two endless conveyor bands mounted below the screening means, the conveyor bands each comprising a center dividing web separating the sand and the ballast on adjacent portions of the conveyor band to convey the separated sand and ballast to the exposed sub-grade section and to deposit the separated sand thereat a point ahead of a succeeding point where the separated ballast is de posited,

4. means for sweeping sand off the ties and for planing the sand on the exposed sub-grade, said means being arranged between said points, and

5. a ballast guiding device associated with each conveyor band at the succeeding point.

5. The apparatus of claim 4,. further comprising means for pivoting each of the endless conveyor bands in a substantially horizontal plane.

6. The apparatus of claim 4, wherein one of the endless conveyor bands is associated with each of the track rails and extends therealong, the conveyor band portions facing the center of the track conveying the sand.

7. The apparatus of claim 4, wherein the means for sweeping sand off the ties comprises a longitudinal carrier means extending along and above each of the track rails, and a plurality of successive plow-like wiping plates mounted on the carrier means and extending transversely thereof.

8. The apparatus ofclaim 4, wherein the sandplaning means is vertically adjustably mounted on the removing means. 

1. A method of stabilizing the sub-grade of a railroad ballast bed, comprising the sequential steps of
 1. depositing sand on the ballast bed,
 2. removing the sand and ballast in admixture until the subgrade has been exposed,
 3. separating the sand and the ballast from each other,
 4. depositing the separated sand in a layer on the exposed subgrade, and
 5. depositing the separated ballast on the layer of sand.
 2. removing the sand and ballast in admixture until the sub-grade has been exposed,
 2. The method of claim 1, wherein ties fastened to track rails are supported on the ballast bed and some of the separated sand is deposited on the ties during deposition on the sub-grade, comprising the further steps of sweeping the sand off the ties and planing the sand down on the exposed sub-grade.
 2. screening means associated with the removing means, the screening means receiving the mixture and separating the sand from the ballast,
 3. at least two endless conveyor bands mounted below the screening means, the conveyor bands each comprising a center dividing web separating the sand and the ballast on adjacent portions of the conveyor band to convey the separated sand and ballast to the exposed sub-grade section and to deposit the separated sand thereat a point ahead of a succeeding point where the separated ballast is deposited,
 3. The method of claim 1, wherein ties fastened to two track rails are supported on the ballast bed and the separated sand is deposited between the rails while the separated ballast is deposited on the layer of sand by throwing at least a major portion of the separated ballast in the region of the ties ends and plowing it inwardly between the rails.
 3. separating the sand and the ballast from each other,
 4. depositing the separated sand in a layer on the exposed sub-grade, and
 4. An apparatus for stabilizing the sub-grade of a railroad ballast bed supporting ties fastened to track rails, comprising
 4. means for sweeping sand off the ties and for planing the sand on the exposed sub-grade, said means being arranged between said points, and
 5. The apparatus of claim 4, further comprising means for pivoting each of the endless conveyor bands in a substantially horizontal plane.
 5. a ballast guiding device associated with each conveyor band at the succeeding point.
 5. depositing the separated ballast on the layer of sand.
 6. The apparatus of claim 4, wherein one of the endless conveyor bands is associated with each of the track rails and extends therealong, the conveyor band portions facing the center of the track conveying the sand.
 7. The apparatus of claim 4, wherein the means for sweeping sand off the ties comprises a longitudinal carrier means extending along and above each of the track rails, and a plurality of successive plow-like wiping plates mounted on the carrier means and extending transversely thereof.
 8. The apparatus of claim 4, wherein the sand planing means is vertically adjustably mounted on the removing means. 